The present invention is drawn to the area of ink-jet imaging. More specifically, the present invention is drawn to pigment-based inkjet ink methods and systems that provide improved image durability, including improved dry rub resistance.
Inkjet printing has become a popular way of recording images on various media surfaces, particularly paper. Some of these reasons include low printer noise, capability of high-speed recording, and multi-color recording. Additionally, these advantages can be obtained at a relatively low price to consumers. However, though there has been great improvement in ink-jet printing, accompanying this improvement are increased demands by consumers in this area, e.g., higher speeds, higher resolution, full color image formation, increased stability, media flexibility, etc.
In general, ink-jet inks are either dye- or pigment-based inks. Both are typically prepared in a liquid vehicle that contains the dye and/or the pigment. Dye-based ink-jet inks generally use a liquid colorant that is usually water-based to turn the media a specific color. Conversely, pigmented inks typically use a solid or dispersed colorant to achieve color.
Many properties that are desirable for inkjet printing include good edge acuity and optical density of an image on a media substrate, good dry time of the ink on the substrate, adhesion to the substrate, lack of deviation of ink droplets when fired, presence of all dots, resistance of the ink after drying to water and other solvents, long-term storage stability, good dot size and dot gain, color-to-color bleed alleviation, acceptable coalescence, long term reliability without corrosion or nozzle clogging, good lightfastness, good waterfastness, low humid hue shift, and other known properties. Many inks are known to possess some of the above described properties. However, few inks are known that possess all of these properties, since an improvement in one property often results in degradation of another property. Accordingly, investigations continue into developing ink formulations that have improved properties and that do not improve one property to the significant detriment of another.
When compared to dye-based ink jet inks, pigmented inkjet inks typically provide superior text quality, line edge acuity, and image durability in many areas including lighffastness and waterfastness. However, pigmented inks, particularly when printed on smooth surfaces such as offset coated media, have poor dry rub resistance. This is a problem that needs to be overcome.
It has been recognized that the use of certain components in ink-jet ink systems can provide good image permanence and smudge resistance, including dry rub resistance. It has also been recognized that certain components for use in such systems can be formulated for use with good reliability using an ink-jet pen. It has also been recognized that a method of providing smudge resistant images using the above system, or a like system, would be advantageous in the art.
Specifically, a system for printing durable ink-jet images having good rub resistance can comprise a substrate, a first ink-jet pen, and a slip component. The first ink-jet pen can contain an ink-jet ink configured for being jetted onto the substrate and can comprise a first liquid vehicle, and an effective amount of a pigment colorant. The slip component can be configured for being coated over the ink-jet ink once the ink-jet ink is jetted onto the substrate.
In an alternative embodiment, a method of printing a durable ink-jet ink image can comprise the steps of jetting a pigment-based ink-jet ink onto a substrate to form a printed image, and overcoating the image with a slip compound.